Excess lipid accumulation in non-adipose tissues is associated with cellular dysfunction and cell death that may contribute to the pathogenesis of insulin resistance, non-alcoholic steatohepatitis, and cardiomyopathy in diabetes and obesity. Mechanisms involved in these pathophysiological responses have been studied in cultured cells by supplementation of growth media with high concentrations of free fatty acids. The saturated fatty acid, palmitate, leads to apoptosis in cultured cells by a mechanism involving oxidative and endoplasmic reticulum stress. This proposal will test the hypothesis that cells with gene disruptions that prevent lipotoxic cell death may have defects in fatty acid import, in fatty acid channeling, in lipid-induced oxidative stress, or in the response to perturbations of endoplasmic reticulum structure and function. Our first two aims will employ biochemical and genetic approaches in cultured cells to identify molecular targets and signaling pathways in the lipotoxic response. In our third aim, we will translate our findings to mouse models relevant to diabetic cardiovascular disease, in which lipid accumulation in cardiomyocytes is associated with heart failure. The results of these studies will provide new insights into the lipotoxic response to excess lipid accumulation in non-adipose tissues in diabetes and obesity. PUBLIC HEALTH RELEVANCE: Heart failure is a serious medical complication of obesity and diabetes that is linked to alterations in fat metabolism in the heart. The studies proposed in this application will characterize how excess fat leads to dysfunction and death of cells and extend these findings to genetically modified mouse models of diabetes and obesity to understand how these mechanisms affect heart muscle function. Given the prevalence of heart failure in diabetic and obese patients and its associated morbidity and mortality, further understanding of this disease process will facilitate the development of new treatments and preventative strategies.